NASA Technical Reports Server (NTRS) 19810009010: NASA's high efficiency and radiation damage solar cell program

NASALS HIGH EFFICIENCY AND RADIATION DAMAGE SOLAR CELL PROGRAM

Lynwood P. Randolph

National Aeronautics and Space Administration
Washington, D. C.

ABSTRACT

The NASA High Efficiency and Radiation Damage (HERD) Solar Cell Program
has the objective of improving the conversion efficiency and increasing the
end of life efficiency of solar cells and arrays for space applications. The
accomplishment of this objective rests upon developing and applying an
improved understanding of the conversion of electromagnetic radiation to
useful forms of energy. To this end a broad range of advanced concepts are
being evaluated.

The research and technology under this program is conducted by four
NASA Centers: Jet Propulsion Laboratory (JPL), Langley (LaRC), Lewis (LeRC),

and Marshall (MSFC). The elements of NASA program are closely coordinated
with similar activities under DOD and DOE sponsorship. This cooperative
effort is focussed on a number of key milestones for both cells and arrays
as shown in figure. Among these two major components the cell work stresses
silicon, gallium arsenide, and multibandgap materials; the array technology
includes both planar and concentrator tasks, annealable arrays and advanced
systems. In addition related work includes updating the solar cell radiation
handbook and maintaining a national testing capability.

Ihe major thrusts of the JPL work are to develop pilot cell production
capability for the thin (50mm) Si cell, develop advanced high performance
GaAs cells, advance the state-of-the-art of efficient array structures,
develop the technology for blankets with a specific power greater than
300 W/kg, develop the technology for concentrator arrays, and to conduct
subsystem testing of cells. In addition another important activity is to
monitor DOE technology for applicability to space cells.

The LaRC program is devoted at this time to GaAs cell activities. The
thrusts include radiation damage and annealing studies, thin cell development
using CVD and graphotaxy and developing the technolo^ for high temperature
operations .

The LeRG program's major thrust are to produce an 18%-AMO-ef f icient
silicon solar cell, reduce the radiation damage suffered by silicon solar
cells in space, develop high efficiency wrap-around contact and thin (50mm)
silicon cells for space use, develop GaAs solar cells for concentrator
applications, investigate the feasibility of 30% iyyiO solar energy conversion
and develop reliable encapsulants for space blankets.

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The MSFC activity is focussed on evaluation of advanced systems for
high power applications. Current concepts under study are the spectrophoto-
voltaics and thermophotovoltaics.

The NASA HERD Program encompasses a range of activities from fundamental
science and engineering to applications of advanced technology. The need
for future research and technology is evidenced by continuing challenges
faced in this important endeavor.

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HIGH EFFICIENCY AND RADIATION DAMAGE (HERD)

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